Radial resonator with bass-note propagator



Nov. 19, 1929.

M. R. HUTCHISON RADIAL RESONATOR WITH BASS NOTE PROPAGATOR Filed Aug. 4, 1927 I N V EN TOR. 371716, Reese flazcbison Y 31 MM A T TORNEY.

Patented Nov. 19, 1929 UNITED STATES MILLER REESE HUTCHISON, OF WEST ORANGE, NEW JERSEY, ASSIGNOR, BY MESNE.

PATENT OFFICE ASSIGNMENTS, TO ACOUSTIC PRODUCTS. COMPANY, OF NEW YORK, N. Y., A COR- PORATION OF DELAWARE RADIAL RESONATOR WITH BASS-NOTE PROPAGATOR Application filed August 4, i927. Serial No. 210,552.

The invention relates in general to acoustic apparatus, and more particularly to a loud speaker which will faithfully reproduce both the bass and'trebleinotes. a

In loud speakers of the multiple horn type in order to reproduce both the bass and treble notes with fidelity and-to render pure sweet tones of every audible pitch, it is desirable from thestandpoint of faithful reproduction to select the longer horns or pipes, since they have low fundamental periods. Horns or pipes do not satisfactorily resonate notes below the fundamental in the musical scale but do resonate quite readilythe harmonics or overtones of the fundamental. The large horns, therefore, resonate both bass and treble notes quite satisfactorily. However, from the standpoint of economy and appearance, large horns are undesirable, since they are expensive to manufacture and take up considerable space.

Sounding boards, on the other hand, have the property of resonating bass notes readily and satisfactorily butdo not resonate the treble notes satisfactorily. Hence a sounding board alone is undesirable as a resonator for notes of the entire audible range. I

According to the invention a multiple horn type loud speaker is provided overcoming these objections, being decidedl more economical as to space and manufacture and also pleasing and attractive'in appearance. At the same time these desirable features are obtained, the loud speaker of the invention reproducestones of great purity and renders music most faithfully'throughout the bass and treble portions of the musical scale.

These results and advantages are obtained by selecting smaller'horns of medium fundamental pitch to resonate the treble notes and using in connection therewith an auxiliary resonator, such as a sounding board, for resonating the bass notes. The horns may be arranged in any desired manner and are preferably curved and nested so as to take up a minimum space. A diaphragm which may be of the rigid cone type may be connected to sounding board and the stylus to prevent impression of the higher notes on the sounding board and to allow passage of the bass notes only from the receiver to the sounding board.

The inventionalso consists in certain new and original features of construction and combinations of parts hereinafter set forth and claimed. I v

Although the novel features-which are believed to be characteristic of this invention will be particularly pointed out in the claims appended hereto, the invention itself, as to its objects and advantages, the mode of its operation and the manner of its organization may be better understood by referring to the following description taken in connection with the accompanying drawings forming-a part thereof, in which Fig. 1 is a diagrammatic side elevation partly in section of the loud speaker;

Fig. 2 is a section on the line 2-2 of Fig. 1; and

Fig. 3 is an enlarged detail showing the connection of the stylus to the sounding board, and the manner in which the stylus passes through the horn member.

In the following description and in the claims parts will be identified by specific names for convenience, but they are intended to be as generic in their application to similar parts as the art will permit.

Like reference characters denote like parts in the several figures of the drawings.

A plurality of walls 4 is provided connecting the plates and extending from the opening 3 to the periphery of the plates, these walls being curved and in nested relation to provide a plurality of curved and-nested horns or pipes 5 having open outer ends. These horns are different lengths and each is tuned preferably to a note of the chromatic scale.

Twelve different horns are shown for purposes of illustration, these horns being tuned pitch so that the horns will not be of too :;la'rge a size for-household use.

jiSecuredto the front plate l and around the opening .3 is a, soft elastic washer 6 which may be made of sponge rubber, the washer being preferably cemented to the plate. v Dis- ;,}posed within the Opening and between the 8 plates is a cone type diaphragm 7 having internal elemental re-enforcing ribs 8 extending from its .apex to its base, and also a radial base flange 9, the radial base flange being cemented'to the rubber washer. The cone diaphragm is arranged to have small clearance with-the back plate 2, and the Walls are provided with angular portions 10 which extend close the sides of the diaphragm to insure that the common chamber 11 in which the diaphragm is located is of as small cubic contenta's possible so that the natural period thereof will be beyond the limits of audibility.

A stylus rod 1215' connected to the apex of the cone in any desired manner such as by soldering and extends to an electromag- -netic push-pull'receiver or unit 13, which may be of any well known construction.-

-. The stylus 12 is extended backward loosely" through an opening in the back plate 2, and is provided with a flat foot 14:. The. sounding board 15 is positioned behind the horns and 'a soft resilient and elastic member 16, such back plate and fits closely around the-stylus as sponge rubber, is cemented to the sounding board at 17, and to the foot 14 at 18. Asoft resilient washer 19 is secured to the 12 so as to make a tight, soundproof joint without binding the stylus. It will be un'der stood that a suitable frame (notflshown) 'niay' be provided on which all the parts are mounted.

Sound horns readily resonate the fundamental to which they are tuned and also. the

harmonics or overtones of the fundamental; I They do not respond readily, however, to

notes below the fundamental. If hornsalone werepsed as the resonance devices, it would be necessary to make them large enoughto resonate the lowest notes it is desired to reproduce. Low pitch pipes or horns are quite large and bulky and for this reason are not entirely suitable for household use.

I A sounding board, on the other hand, res

onates the low or bass notes quite readily, but,

does not readily resonate the treble or higher notes. The horns and sounding board thus supplement each other and by usingboth to- 'gethcr it is possible to obtain very satisfactory results with smallerhorns'resonating fundamental notes of middle pitch. This combination, therefore, allows the use of the considerably smaller horns of middle pitch without sacrificing any faithfulness in reproduction.

The sponge rubber 16 operates as a low 1 pass filter and'allows the .low pitch or bass notesto be transmitted from the stylus 12 to the sounding'board 15 but does not pass the higher pitch notes. A single receiver is used and treble notes; The diaphragm vibrates as a, unit and accurately transmits to the surrounding niediumrthe compressions and rarefactions which are delivered thereto from the reCeiVel. ll soft washer 6 allows free movement offthe diaphragm'en masse and provides-a sound proof joint. The sound wavesjarepropagated at an angle of 45 degrees toithe diaphragi'n or in the plane of the horns." E

ach note above middle pitch will be readilyjrejsonated by some horn or pipe and notes below middle pitch will be resod bythe sounding board. [The washer 19 seals the opening through .whi'ch thestylus passes without binding the stylus. The soft member 16 operates as a low pass filter to pass the low notes to and exclude the higher notes from the sounding board. The parts are so arranged that there will be no binding to cutdown.the'eihcicncy and no loose connections to cause rattling and noise. Although the device has been described as a loud speaker and is especially designed for such use, it will be understood that it is also \Vhilc certain novel features of the inven- L tion have been shown and described and are pointed out in the annexed claims, it will be understood that various omissions, substitut-ions and changes in the forms and details of the device illustrated and in its operation may be made by those skilled in the art without departing from the spirit of the invention.

What is claimed is: 1; In acoustic apparatus, a casing having an opening, a plurality of pipes of different lengths communicating with said casing, a diaphragm over said opening, a stylus connected to said diaphragm and passing through said casing, a receiver in front of said casing and connected to said stylus, a sounding board behindsaid casing, and a low pass filter connecting said board and stylus.

' 2. In acoustic apparatus, a casing having an opening, a plurality of pipes of different lengths communicating with said casing, a cone diaphragm over said opening, a yieldable member between said diaphragm and casing, a receiver, a stylus connecting said diav phragm and receiver, a soundingboard, and

a low pass filter connecting said board and stylus.

V 3. In acoustic apparatus, acasing, a plurality of horns arranged to resonate the higher notes and communicating withsaid casing, a rigid diaphragm, a yieldable joint between said diaphragm and casing, a sounding board, actuating means, a stylus connecting diaphragm and said means, and a soft yicldablc member operating as a low pass filter connecting said stylus and said board. 4. In acoustic apparatus, a pipe resonatlng device, a sounding board, an energy transfer device, and means for operatively connecting said devices and board. r

5. In acoustic apparatus, a pipe resonating device, a sounding board, an energy transfer device, and means for operatively connecting said devices and board, and a low pass filter between said transfer device and board. p

6. In acoustic apparatus, a casing having an opening, a plurality of pipes of different lengths communicating with said casing, each pipe resonating a different note of middle pitch,a yieldable member secured to said casing around said opening, a rigid diaphragm secured to said member,.an actuating means in front of said casing, a stylus rod connectedto said diaphragm and operatively to said means, said styluspassing through a wall of said casing, a soft washer secured to said walland sealing'the opening through whichthe stylus passes, a sounding board in back of said casing and a piece of soft yieldable material between said board and stylus to actas a low pass filter.

7. In acoustlc apparatus, a'pair of front and backplates, said front plate having an opening, a pluralityof nested curved walls connecting said plates and extending from said opening to'the outer edges of said plates and forminga plurality of pipes of different lengths each resonating a different note of middle pitch, a soft yieldable Washer cemented to said front plate around said opening, a. cone diaphragm having a radial base flange cemented to said washer, said diphragm extending within the space between said'plates,

an'actuating means in front of said plates, a

stylus rod connected to the apex of said diaphrag'm and operatively to said means, said stylus passing through said back plate, a soft washer secured tosaid plate and sealing the opening through which the stylus passes, a sounding board in back of said plates, said stylus having a foot, and a piece of soft yieldable material cemented to said board and foot to actas a low pass filter.

. York and State of New York this 2 day of Signed at New York in the county of New August, A. I). 1927.

MILLER REESE HUTCHISON. 

